Container base



FIG. 1 is a perspective view of a container base showing my new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a side view thereof;

FIG. 5 is a top view thereof; and,

FIG. 6 is a bottom view thereof. 

CLAIM The ornamental design for a container base, as shown and described. 